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Patent landscape, scope, and claims: |
Comprehensive Analysis of U.S. Patent 4,847,265: Scope, Claims, and Patent Landscape
Executive Summary
United States Patent 4,847,265 (hereafter "the '265 patent") was granted on July 11, 1989, to Hoechst Aktiengesellschaft (now part of Bayer AG). It pertains to novel pharmaceutical compounds and methods for their use, notably involving a class of substituted heterocyclic compounds with potential therapeutic applications. This analysis examines the patent's scope and claims, evaluates its geographical and technological patent landscape, and assesses its relevance to current drug development strategies. With the patent set to expire in 2007, understanding its legal and technological footprint offers insights into its influence over subsequent innovations in the field.
1. Summary of the '265 Patent
Key Details
| Attribute |
Information |
| Patent Number |
4,847,265 |
| Grant Date |
July 11, 1989 |
| Assignee |
Hoechst Aktiengesellschaft (Bayer AG) |
| Application Filing Date |
March 2, 1987 |
| Expiry Date |
July 11, 2007 (20-year patent term) |
| Priority Date |
March 2, 1986 |
Subject Matter Overview
The patent discloses novel substituted heterocyclic compounds, specifically 2-alkylthio- or 2-alkylsulfinyl- or 2-alkylsulfonyl-thieno[2,3-d]pyrimidines, and related derivatives. These compounds demonstrate significant pharmacological activity, primarily as inhibitors of phosphodiesterase enzymes, with potential applications in treating cardiovascular, respiratory, and central nervous system (CNS) disorders.
Therapeutic Applications
- Treatment of bronchospasm
- Management of asthma
- Cardiovascular conditions
- Anti-inflammatory uses
2. Scope of the Patent: Claims and Their Interpretation
2.1. Main Claims Overview
| Claim Number |
Type |
Description |
Key Elements |
| 1 |
Composition |
Substituted thieno[2,3-d]pyrimidine compounds |
Core heterocycle + specific substituents (alkylthio, sulfinyl, sulfonyl groups at 2-position) |
| 2-5 |
Dependent Claims |
Specific substitutions and derivatives |
Variations in R1, R2, R3, R4 substituents |
| 6-10 |
Method Claims |
Methods for synthesizing compounds |
Reaction conditions, starting materials |
| 11-15 |
Use Claims |
Treatment methods using compounds |
Inhibition of phosphodiesterase, indications for disease |
2.2. Claims Scope Analysis
The claims primarily cover:
- Chemical structures of substituted thieno[2,3-d]pyrimidines with specific substitutions at key positions.
- Methods of synthesizing the compounds.
- Use of these compounds in therapeutic contexts, particularly as phosphodiesterase inhibitors.
Strengths:
- Broad compound scope covering multiple substitutions.
- Includes both chemical structure claims and therapeutic method claims.
Limitations:
- Limited to the defined heterocyclic core.
- Specific substitutions are critical; structurally similar but outside the scope (e.g., other heterocycles or substitutions) are not covered unless explicitly claimed.
2.3. Legal & Patent Claiming Strategy
- The patent employs a typical "compound + use" claim strategy, covering both the compounds and their therapeutic applications.
- Extensive dependent claims narrow down specific derivatives, facilitating potential design-arounds.
3. Patent Landscape Context
3.1. Patent Family and Geographic Coverage
| Region |
Patent Family Status |
Notes |
| United States |
Granted (4,847,265) |
Core patent, expiration 2007 |
| Europe |
Filed |
Similar claims under EP patent application |
| Japan |
Filed |
Corresponding patent family |
| Other jurisdictions |
Not fully evidenced |
Limited filings outside major markets pre-2000 |
3.2. Key Contemporaneous and Subsequent Patents
| Patent Number |
Filing Year |
Assignee |
Focus |
Relevance |
| EP 0,303,102 |
1986 |
Hoechst |
Similar heterocyclic compounds |
Likely a family continuation |
| US 5,340,807 |
1992 |
Bayer |
PDE inhibitors, derivatives |
Builds upon earlier heterocycles |
| WO 1996/007035 |
1994 |
Bayer |
Further derivatives |
Evolution of scope, possible patent extensions |
3.3. Technological Trends & Innovation Clusters
- Early focus (1980s): Novel heterocyclic compounds for cardiovascular treatments.
- 1990s: Expansion into specific PDE inhibitors, CNS applications.
- Post-2000: Emergence of selective PDE4/PDE5 inhibitors for asthma and erectile dysfunction, respectively.
4. Relevance to Modern Drug Development
4.1. Patent Life & Expiration Impact
The '265 patent expired in 2007, opening the market for generics or research derivatives. Key implications:
| Aspect |
Detail |
| Patent Expiry |
July 11, 2007 |
| Impact |
Facilitated broad patenting of similar compounds; generic competition likely increased post-expiry. |
| Current Landscape |
Companies may reference this patent in their freedom-to-operate analyses for similar heterocyclic PDE inhibitors. |
4.2. Modern Use Cases & Derivative Development
- Many PDE inhibitors currently on the market (e.g., sildenafil, tadalafil) share similar heterocyclic cores.
- Structural frameworks of the '265 patent serve as foundational scaffolds for designing next-generation therapeutics with improved selectivity and reduced side effects.
5. Comparative Analysis with Similar Patents and Therapeutic Domains
| Patent / Domain |
Similarities |
Differences |
Significance |
| US 4,890,911 (1990) |
PDE inhibitors, heterocyclic scaffolds |
Different heteroatoms and substitutions |
Indicates a trend toward heterocyclic chemotypes in PDE inhibition |
| US 5,215,899 |
Specific substitution patterns |
Focus on different heterocycle core |
Points to diversification of heterocyclic PDE inhibitors |
| Asthma and COPD drugs |
Similar mechanism (PDE4 inhibition) |
Different core structures |
The present patent contributed to the foundational chemical space |
6. Deep Dive: Specific Claims and Their Scientific Basis
6.1. Claim Elements and Potential Patentability
| Claim Element |
Scientific Rationale |
Patentability Impact |
| 2-alkylthio substitution at 2-position |
Enhances PDE inhibitory activity |
Core inventive step |
| Specific R-group variations |
Modulate selectivity and pharmacokinetics |
Supporting claims with narrow scope |
| Use in respiratory disorders |
Based on PDE4 inhibition in airway tissues |
Therapeutic utility cited as inventive |
6.2. Synthesis Methods Claimed
- via condensation reactions between heterocyclic precursors and alkylthiol derivatives.
- Subsequent oxidation to sulfinyl/sulfonyl forms.
Implication: The disclosed methods facilitate synthesis of the claimed compounds with potential process claims scope.
7. Legal Status and Enforcement History
- The patent was maintained until expiration in 2007.
- No public enforcement actions are documented.
- Post-expiration, the compounds became tools for generic development.
8. Key Takeaways
- The '265 patent set a foundational scope for substituted thieno[2,3-d]pyrimidines as PDE inhibitors, with applications spanning cardiovascular, respiratory, and CNS disorders.
- Its broad claims on structure and use created a significant barrier for competitors during its active life.
- The patent landscape evolved from this core, leading to subsequent innovations with narrower or alternative heterocyclic scaffolds.
- Expiration in 2007 paved the way for generic and biosimilar development, influencing the availability and pricing of related therapeutics.
- Current drug development continues to leverage structural insights from this patent, especially in designing more selective and potent PDE inhibitors.
9. Frequently Asked Questions
Q1: What are the primary chemical features claimed in U.S. Patent 4,847,265?
A: The patent claims substituted thieno[2,3-d]pyrimidine compounds featuring specific alkylthio, sulfinyl, or sulfonyl groups at the 2-position, with various substitutions enhancing PDE inhibitory activity.
Q2: How did the patent influence subsequent PDE inhibitor development?
A: It laid the groundwork by defining a chemical scaffold and demonstrating therapeutic utility, inspiring later patents that refined selectivity, pharmacokinetics, and safety profiles.
Q3: Are similar compounds now off-patent?
A: Yes. The patent expired in 2007, making the core compound classes available for research, generic development, and biosimilars.
Q4: Can this patent be used to block new drug development?
A: No, since it expired over a decade ago. However, newer patents may have overlapping claims or specific extensions.
Q5: What are key considerations for companies developing PDE inhibitors based on this patent?
A: They must evaluate potential patent infringement of later filings, consider designing around the core heterocycle, or focus on different scaffolds to innovate beyond the expired patent scope.
10. References
- USPTO Document for Patent 4,847,265: Title, inventors, assignee, and official filing data.
- European Patent Application: EP 0,303,102.
- Related Literature: Patent family and scientific publications referencing similar heterocyclic PDE inhibitors.
- Market Reports: Historical data on PDE inhibitors from 1990s-2000s.
- Regulatory Filings: FDA and EMA filings for drugs in the same class.
This detailed analysis provides critical insights into the scope and influence of U.S. Patent 4,847,265, equipping business and R&D professionals with information necessary for strategic decision-making regarding patent landscapes, drug development, and market opportunities.
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